if the diameter of the can is 6 cm, then its radius is half that, or 3 cm.
[tex]\bf \textit{surface area of a cylinder}\\\\
SA=2\pi r(h+r)~~
\begin{cases}
r=radius\\
h=height\\
-----\\
r=3\\
h=12
\end{cases}\implies SA=2\pi (3)(12+3)
\\\\\\
SA=6\pi (15)\implies SA=90\pi [/tex]
